Abstract

A safe and effective vaccine against HIV is desperately needed, particularly in developing countries where more than 90% of infections occur. Peptide vaccines are safe and chemically well-defined, providing an alternative strategy to conventional vaccines. A couple of such potential antigens are the 24 kDa core protein p24 and the 31 kDa regulatory protein Nef. Plants offer several advantages for the production of high value proteins, including lack of contamination with animal pathogens, relative ease of genetic manipulation, and eukaryotic protein modification machinery. In comparison to current production systems, large amounts of these antigens can be produced at relatively low cost in agriculturally-based systems. The high levels of expression obtained through chloroplast transformation, in particular, will reduce the amount of plant material required for vaccination. The aim of this project is to assess the immunogenicity in mice of chloroplast-derived HIV -1 p24 and Nef. Comparisons between expression levels in chloroplasts of both antigens in tobacco cultivars transformed with various constructs have provided important information concerning vector optimization, choice of cultivar and protein accumulation. These plant-expressed antigens have been administered subcutaneously, nasally and orally to mice. Serum analysis and proliferation data have shown good immune responses